The number 1 rule to this
YOU CAN NOT ABSOLUTELY CAN NOT NO MATTER HOW WORRIED YOU ARE, SCARED YOU ARE, ETC. FORCE HIM TO QUIT!
Personally I have seen cancer patients not care and keep smoking, THIS IS AN ADDICTION NOT A DANG HABIT SO GET THAT OUT OF YOUR HEAD! We can't just quit it like a dime, it's an addiction that we recover from. WE ARE ADDICTS!
Second once he MAKES HIS OWN DECISION TO QUIT SMOKING.....then support him like offer to help him when he needs it, listen to him, etc.
Listen no doctor, not you, not anybody is going to do this but him! I've seen people divorce because the other one won't quit smoking again this is an addiction. If you don't want to put strain on your marriage and possibly end up in the courthouse due to ww3 due to your nagging about his smoking........I suggest you lay off of him until HE MAKES THE DECISION ON HIS OWN!
Of course this is just coming from someone who quit, someone who is going through the withdrawal now! Unlike habits, habits don't have withdrawals addictions do! Habits are easy to break, addictions aren't.........My husband is continuing to smoke and you know what let him. What he does doesn't effect my quit!